Synthesis,Characterization And Performance Study Of Bisbenzimidazole Metal Complexes

Metal complexes have attracted attention due to the flexibility of their coordination modes,structural diversity,novel topological structures and the wide range of applications.Reasonable ligand selection is particularly important in application.We designed and synthesized four bis-benzimidazole ligands,and introduced different aromatic carboxylic acids,synthesized nine bisbenzimidazole compounds with different transition metals via solvothermal/evaporation methods.The structure of the complex was analyzed by single crystal X-ray diffraction,powder X-ray diffraction and infrared spectroscopy,and the thermal stability,dielectric properties and fluorescence properties of the chemical structure of the complex were studied.The effects of organic ligands in different configurations on the properties of the complexes are also discussed.（1）By solvothermal/evaporation method,three complexes were constructed using bisbenzimidazole ligand（H₂MBIM）with transition metal.Among them,compound 1,2 and3 are all zero-dimensional monomolecular structures.Interestingly,the methylene group in the organic ligand is oxidized to a carbonyl group in compound 1 and 2,and the central carbon atom has the initial sp³hybridization transform to the current sp²hybridization,which in turn increases the molecular out-of-ring conjugation effect.In complex 3,the methylene group formed carbon-carbon double bond by dehydrogenation,and theoretical calculations verified the possibility of the formation of a carbon-carbon double bond.This may method become a novel synthesis of carbon-carbon double bonds.（2）By solvothermal method,four metal coordination polymers are constructed using semi-rigid bisbenzimidazole（BMB）with transition metals.Among them,complex 4possesses one-dimensional（1D）chain structure,and there are two mutually chiral chains;complexes 5,6,and 7 are all three-dimensional（3D）MOFs（Metal organic frameworks,MOFs）structures.Interestingly,semi-rigid benzimidazole ligands exhibit cis and trans structures in different complexes due to their unique structure.Complex 4 exhibits trans structure,complex 5 exhibits cis structure,and complexes 6 and 7 exhibit both cis and trans configure.At last,through the calculation of molecular occupied orbital research.（3）By solvothermal method,two complexes were constructed using bisbenzimidazole derivatives（BBIM-2A）and flexible benzimidazole（H₂EBIM）with transition metals.Among them,the complex 8 has a two-dimensional（2D）planar structure.Unfortunately,the central copper atom does not coordinate with the allyl group to form alkene-copper structure;the complex 9 has a one-dimensional（1D）chain structure,due to the unique structure of the ligand.The regulation of terephthalic acid forms two chains that are chiral to each other like complex 4.In this thesis,four bisbenzimidazole ligands were designed,modified and synthesized,and nine complexes were constructed with transition metals.Their structures were characterized.The thermal stability,dielectric properties and fluorescence properties study were correlated.